Telephone lockout system.



F. w. ADSIT. TELEPHONE LOCKOUT SYSTEM.

APPLICATION FILED MAYI, 1915.

Peeentea Feb. 20,1917. Y

Cit

FRANK W. ADSIT, OF MINNEAPOLIS, MINNESOTA.

TELEPHONE LOCKOUT SYSTEM.

Specification of Letters Iatent.

Patented Feb. 20, 1917.

Application filed Maypl', 1915. Serial No. 28,632.

To all whom t may concern:

Be it known that l, FRANK W. ADsrr, a citizen of the United States, residing at Minneapolis, in the county of Hennepin and State of Minnesota, have invented certain new and useful Improvements in Telephone Lockout Systems, of which the following is a specication.

My invention relates to means for preventing parties on a telephone party line from listening in on the lineV whenit is in use by another subscriber, and refers more' particularly to that class of telephone lines rnown as common battery or central energy Vmes.

The drawing, which forms a part of this specification, discloses a pair of line wires A adapted to be connected to any type of co1nmon-battery exchange.

At stations 1, 2 and 3,.the ordinary common-battery telephone set such as 4, 4', 4", is connected by wires 5, 5', 5" to one side of the line A, and the other side of the telephones are connected to the lock-out attachments G, 6', 6" by wires 7, 7', 7", respectively. The other side of the line A is brought into the lock-out attachments by wires 8, 8', 8" and 9, 9', 9".

When the subscriber at station 2 removes his receiver from the hook, current is fed out onto the line A through any suitable means at the exchange, and passing through the winding 10', wir@ 11', contact 12', wire 8', completes the circuit and serves to signal the central operator a connection is wanted.

It will be noted that the armature 13' will be attracted by the coil 14', thus opening the contact 15', which is of the type ordinarily called a follow contact and does not break until the contact 16' has been made.

The opening of the contact 15' renders stations 3 and 3' inoperative, as it has opened one side of the line leading to these two stations.

The current flowing on the line A through the set 4' at station 2 also flows through the winding 20 at station 1, Contact 15, and out to the line again on wire 8, thus operating the armature 23 by its attraction to the core 24, in this manner rendering the telephone 4 at station 1 inoperative through the opening of the Contact 12.

The operation of each attachment is identical. The control of the telephones between a particular station and the exchange is maintained by the operation of the righthand coil, as disclosed in the drawing, in each instrument so controlled, and this control over the right-hand coils in the instruments toward the station is due to the current flowing through these coils and the telephone set at the station initiating the call, vthe current at this station flowing through the left-hand coil, as disclosed in the drawing.

The control of stations farther from the exchange than the one initiating the call is directly accomplished by the contact which is broken when the left-hand coil at the station initiating the call is operated.

The windings 10, 10', l0" are preferably of a high resistance and a correspondingly high number of turns to render the coils operative on systems using a high-resistance line relay, and the windings 17, 17 17" are of low ohmic resistance, but have suilicient ampere turns to maintain the contacts 16, 16', 16" after the vcoils 14, 14', 14" have been operated.

The windings 17, 17', 17", being of low ohmic resistance, afford a suflicient current supply for battery feed, and the non-inductive windings 18, 18', 18" are utilized to allow the voice currents to pass through the attachment more readily than would the inductive windings17, 17', 17' Y It will be noted that only three attachments are necessary for the operation of a line equipped with four telephones, and two attachments will be sufficient to take care of a three-party line, and, similarly, one attachment would take care of a two-party line.

In case of a revertive call, where station 3 was calling station 2 on the same line, for example, the central operator would be signaled in the usual manner, but would inform the subscriber the call was on his own line andV ask him to hang his receiver on the hook while the party .wanted was being rung.

If the party called responds while the bell is still being rung, and the party calling also takes his receiver from the hook while the ringing current 1s on the line,

neither partys set will be operative until the operator removes thc ringing current by the usual manner of throwing her ringing key, as the ordinary practice is to have the line dead or free from battery current 'when the ringing current is on. When the battery current is restored to the line through the restoring of the ringing key to its norinal position, the current at station 2 will flow through both coils, hence both arinatures 13 and 23 Will be actuated, and the party at station 2 Will be in on the line. The party at station 3 will be connected to the line with the party at station 2 in a siinilar inanner, While parties beyond station 3 Will be cut oii' through the opening of contact 15 and parties between station 2 and the exchange will be cut oi by the operation of the right-hand coil at each station, as shown in the drawing.

lVliile l have described and illustrated my invention with one particular arrangement of parts and circuit, ll do not wish to be understood as limiting niyselilf to this particular arrangement, as it is evident the saine result may be accomplished by a ninnber of different arrangements Within the scope of my invention as set forth in the following claims.

I cla-iin: Y

l. In a telephone lock-out systeii'i, the combination oi a pair of line Wires adapted to be connected to a common-battery exchange, two subscribers stations associated with said pair of line wires, ineans associated with one of said stations to disconnect the other of said stations when the first of line circuit, a lockeout mechanism connect ed with said line circuit and said stations and adapted to disconnect either of said stations when the other station is actuatgl7 and ineans in said lock-out mechanism adapted to connect both of said stations to said line circuit when battery is applied to said line circuit after both of said stations have been actuated.

FRANK W. ADST.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

